class Solution {
    public int romanToInt(String s) {
        int sum = 0;
        for(int i = 1;i<s.length();i++) {
            int ret1 = getValue(s.charAt(i-1));
            int ret2 = getValue(s.charAt(i));
            if(ret1>=ret2) {
                sum+=ret1;
            }else if (ret1<ret2){
                sum-=ret1;
            }
        }
        return sum + getValue(s.charAt(s.length()-1));
    }
    public int getValue(char ch) {
        switch(ch) {
            case 'I' : return 1;
            case 'V' : return 5;
            case 'X' : return 10;
            case 'L' : return 50;
            case 'C' : return 100;
            case 'D' : return 500;
            case 'M' : return 1000;
        }
        return 0;
    }
}